1. Field of the Invention
The present invention relates generally to an apparatus for providing a visual indication of a current location of a mobile craft. More particularly, the invention relates to an improved apparatus having a visual indicating function of a current location of an automotive vehicle or the like for providing a visual display of combined information, such as a current travel status of the vehicle in terms of a current location, a path of travel, a travel direction, etc., for the driver or operator of the vehicle.
2. Description of Relevant Art
In order to prevent the driver or operator of an automotive vehicle or the like from losing his way when driving at night or in unfamiliar surroundings away from his desired route of travel, there have been proposed a variety of apparatus which are specifically designed to provide the driver with suitable ready guidance relating to the vehicle's current status of travel with reference to the desired course of travel, from time to time during travel, by continuously or discretely indicating a due current position or similar information on the vehicle by way of an indication panel or display screen including a related road map or the like disposed at the driver's seat.
In a typical construction of the conventional apparatus for visually indicating a current location of an automotive vehicle for use in such application, a current travel distance of a vehicle is detected by way of distance detecting means in accordance with the vehicle's current travel speed and time of travel, a current bearing and a current quantity of azimuthal deviation of the vehicle are detected by bearing detecting means, and a current location of the vehicle along its travel route is obtained from arithmetical operation on the basis of the thus-obtained route detection data. The result of such arithmetic operation is stored for visual indication on a display in the form of spot information, which varies from time to time during travel of the vehicle, on a display screen on which there is placed in advance a suitable road map such as printed on a transparent sheet or the like. A comparative review of the thus-indicated visual information and the geographical indication by way of the map sheet is thus permitted, so that the driver of the vehicle may visually confirm the current location of the vehicle along its travel route.
With such a typical construction of the apparatus for use as mentioned above, however, it is commonly required that, in order to obtain a due locational guidance with reference to the current location of an automotive vehicle, the driver of the vehicle must take the trouble of selecting in advance a proper sheet from a plurality of prepared local maps which includes a correct area of travel desired by the operator of the vehicle, so as to be placed in position on the surface of the display. Further, such a map sheet set upon the display screen is likely to randomly shift from its due position during travel of the vehicle due to vibrations, turning motion, etc., which are likely to be frequently encountered during the vehicle's travel. Thus, the map sheet is likely to prove to be awkward and troublesome for the driver or operator.
The present invention effectively overcomes the aforesaid inconveniences and difficulties experienced in selecting and setting one of a set of local area maps as printed on the transparent sheets and to be set upon the display screen in the conventional location detecting apparatus for use in an automotive vehicle.